Telephone system



Jan. 24, 1939.

E. S. PETERSON TELEPHONE SYSTEM Filed Oct. 26, 1936 2 Sheets-Sheet 1 ATTORNEY.

Jan. 24, 1939. E. s. PETERSON 2,145,094

TELEPHONE SYSTEM Filed Oct. 26, 1936 2 Sheet-Sheet 2 J 1: y 5 q r\ ,1 3 2Q i N U (Z 3% I: a 5f l Lu l I 95 N H m o 132% & MN 4 E g I w gm 2' (*1 a L3 N s a 3 0 N Q h- 3 m r w B INVE 'NTOR. 22 9. 2 '1 2 9 EDWARD s. PETERSON ATTORNEY.

Patented Jan. 24, 1939 UNITED- STATES 2.145.094' TELEPHONE SYSTEM- Application October 26,

18 Claims.

This invention relates ingeneral to telephone systems, but is concerned more particularly with operator controlled magneto exchange telephone systems, commonly referred to as remote controlled exchanges, (R. C. X.), in which connections between local subscribers are established by manual operators from a remote or distant control point.

More in particular, the present invention relates to a telephone system wherein an operator at the central oflice may control the switching equipment in an outlying exchange or rural oilice terminating local battery magneto lines either to establish connections between two subscribers in II the rural oflice or to establish connections to the central or main ofllce.

One object of the invention is to provide a' cheap but nevertheless efficient unit for. small rural communities that heretofore have beenwithout any communicating service because the number of subscribers desiring service did not warrant the expense of the installation of aswitching exchange. The switching unit in the present invention is arranged totake care of' twenty subscribers linesrand is controlled over two trunk lines from the distant central omce by a manual operator. The. equipment in the small rural exchange operates on a 12-.volt storage battery which is charged over one of the 80 trunk lines. The release of all of the connections are under control of the remote operator.

Another object of the invention is the provision of improved circuit arrangements, whereby the control of the magneto exchange by the op- 85 erator at the remote omce may be brought about in a thoroughly reliable manner, while the equipment and the number of conductors required between the two exchanges over which the operator controls the setting up of connections between 40 subscribers in the magneto exchange has been reduced to a. minimum.

Other objects and features of the invention will be understood by referring to the specificaand'to the calling subscribers. The dotted square,

shown in the 1' wer right-hand corner of Fig.1

PATENT. OFFICE 1936, Serial No. 107,581

represents circuit arrangements identical with those shown in Fig.2.

Fig. 2 shows the control relays and the minor switch individual to one of the trunk lines, such trunk line extending to' the remote oflice where 5 it terminates in a jack.

The switch shown in the lower portion of Fig. 2 is commonly used in telephone systems and is known as a minor switch having an. operating magnet for advancing the wipers step by step 10 and arelease magnet for restoring the wipers of the switch'to normal position. The relays shown with their lower portions cross-hatched and the relays, such as relays2l0 and 280, shown with 7 copper sleeves around the cores, are of the slow- 1! to-release type. Relay 294 is a thermo relay which closes its contacts 293 a predetermined time after the circuit to this relay has been completed. a

In describing the detailed operation of the ap- 20 paratus shown it will first be assumed that the magneto subscriber SI2 desires to converse with subscriber SII. In order to initiate a call the subscriber SI2 operates his hand magneto in the well known manner and completes a circuit for 25 energizing line relay I20, assuming that'both trunk lines are idle, over the' following circuit: from the hand generator by way of subscribers conductor I92, back contact I5I, back contact I32 of the common cut-off relay I30, left-hand winding of line relay I20, back contact I22, subscribers line conductor I33, to the hand generator. Line relay I20 energizes over the above-traced circuit and at contacts I23 completes a locking circuit in series with relay 200 as follows: from 35 ground by way of contact I23, right-hand winding of relay I20, conductor I04; contacts 2'" and through the winding of relay 200 to battery. At back contact I22 line relay I20 opens its original energizing circuit only after its locking circuit is completed, and at front contacts I2I and I22 connects the subscribers line conductors I92 and I9 3 to' the trunk line conductors I02 and I03.

At front contacts I24'linerelay I20 prepares a point in the circuit for the busy relay I08'in case the called line is busy.

From the foregoing description it will be seen that in response to the subscriber SI2 operating his hand generator the line relay I20 is energized and locked to connect the subscribers line to the upper trunk line. In order to more fully describe the circuit operations it will now be assumed that the upper trunk line is busy at the time subscriber SI2- operates his magneto. In casethe upper trunk line is busy then the common cut-off relay I30 is in operated position and the line relay I50 instead of line relay I will be energized and locked in response to the operation of the hand generator. when subscriber SI2 operates his hand magneto at a time when only the upper trunk is busy then line relay I50 winding in series with the relay corresponding to relay 200 in the apparatus associated with the second trunk line. At back contact I52 line relay I50 likewise opens a point in its original energizing circuit after completing its locking circuit, at front contacts I5I and I52 connects the line conductors I92 and I93 to the lower trunk conductors I12 and I13, and at front contact I54 prepares a point in the circuit for the busy relay In case both the upper and lower trunks are in use, then both of the cut-off relays I 30 and I50 will be in operated position. In case a subscriber should originate a call at Ya time when both trunk lines are busy, then no circuit is completed for energizing either one of the two associated line relays because the circuits for these relays are opened at the contacts of the operated cut-ofl relays.

Returning now to the time when line relay I20 is operated to connect the subscriber's line to the upper trunk, it will be seen that the continued operation of the hand generator transmits ringing current through the repeating coil RCI over the trunk conductors 232 and 233 and the repeating coil RC2 to cause the operation of the drop 234 in order to signal the remote operator. When the operator observes the operated condition of drop 234 such operator will insert a plug (not shown) into the jack J and converse with the calling subscriber. Jack springs 235 are closed in response to the insertion of the plug into the jack J to complete a circuit for line relay 290 in the rural exchange as follows: from ground through the winding of line relay 290, through the lower right-hand winding of repeating coil RCI, trunk conductor 233, lower left-hand winding of repeating coil RC2, through the impulse springs 235 of the dial, and through jack springs 235 to battery. Line relay 290 energizes over the abovetraced circuit and at front contact 29I completes the circuit for release relay 280. Release relay 280 energizes and at contacts 28I closes a shunt around contact 21I, at contact 282 completes the circuit for the hold relay 210, and at contact 283 prepares a point in the impulsing circuit.

The hold relay 210 now operates and at contact 2 opens the original energizing circuit of relay 200 and the locking circuit of line relay I20 only after contacts 28I have placed a shunt therearound. It should be mentioned at this point that relay 200 energizes in series with the locking circuit of'line relay I20 to complete the circuit for energizing the common cut-off relay I30 from ground by way of contact 20I and conductor I 05. At contact 202 relay 200 completes acircuit for energizing the thermo relay 294 by way of contact 213, and at contact 203 completes the circuit for operating the tone relay 2104 as follows: from ground by way of back contact 214, contact 203, through the right-hand winding of tone relay 204, through the resistance to negative battery. Tone relay 204 thereupon operates and at contact 205 short circuits its right-hand .winding to cause its deenergization. Tone relay thereupon operates in the same manner as a buzzer to induce a tone in the left-hand winding which extends through the tone condenser TC and over conductors I02 and I03, throughthe front contacts I 22 and I2I, and conductors I92 and I93, to the calling subscribers substation set, thereby informing the calling subscriber that he has seized an idle trunk line and may again turn his hand generator to signal the distant operator. When the operator answers; as previously described, relay 210 is energized to connect a multiple ground to conductor I05 to maintain the common cut-off relay I30 in energized position, and to open the circuit at contact 213 completedby'relay 200 for the thermal relay 294. At back contact 214 hold relay 210 opens the circuit to tone relay 204, whereupon the tone relay stops vibrating to disconnect tone from the calling line to thereby inform the subscriber that the operator has answered. At front contact 214 hold relay- 210 prepares a point in the energizing and locking circuits of relays 220, 230, 240, and 250, at front contact 215 prepares a point in the circuit for grounding wipers 2I3 and 2I4, and at back contact 215 opens a point in the circuit to the release magnet 2I5 of the minor switch.

When the tone is'removed from the trunk conductors I 02 and I03 the calling subscriber advises the remote operator that a connection is desired with subscriber SI I and thereafter replaces his receiver. The remote operator now operates his dial in accordance with the digits in the called number or in accordance with the digits 1 and 1, since the telephone. number of the called subscriber is'number 11. In response to the operation of the dial in accordance with the first digit 1, the shunt springs 231 are operated to short circuit the right-hand windings of the repeating coil RC2 and the drop 234, and on return of the dial the impulse springs 236 are momentarily opened once to cause the deenergization of line relay 290. At back contact 29I the deenergization of line relay 290 completes the circuit for operating relay 240 and series relay 210 in multiple as follows: from ground by way of back contact 29I, contact 283, contact 252, where the circuit divides, one path going through the winding of series relay 260 to battery, and the other path extending by way ofback contact 25I and through the winding of relay 240 to battery.

Relay 260, upon energizing, at back contact 25I opens a point in the circuit to the operating magnet 2I2 and at front contact 26I prepares a new operating circuit for itself in case the first digit dialled comprises more than one impulse. Relay 240, upon energizing, at contact 24I prepares a point in its own locking circuit as well as a point in the energizing circuit of relay 250. Relay 250 will not energize at this time because this relay is short circuited as follows: from ground by way of'front contact 214, contact 2, winding of relay 250, back contact 25I, by way of back contact 252 or front contact 25I, contact 283, and back contact 29I to ground. Line relay 290 reenergizes when the impulse springs 235 of the dial are closed to reestablish the energizing circuit of slow-to-release relay 280 to maintain it in operated position, and to open the short circuit around relay 250 at back contact 29I.

contact 2, and windings of'relays 260 and 240 to battery. At front contact 25l relay 260 prepares a point in the circuit to relay 220, at contact 252 opens a point in the original energizing circuit of relay 240, and at contact 253 prepares a point in the impulsing circuit to the operating magnet 2l2 of the minor switch. In case the first digit comprises more than one impulse, the series relay 260 is maintained in operated position to complete a circuit for relay 220 by way of front contact 25I, upon the second deenergization of line relay 290. However, inthis case, since the first digit dialled is l, and line relay 280 is not deenergized asecond time, the relay 220 is not at this time energized and the series relay 260 deenergizes after an interval. Relay 260, upon deenergizing, at back contact 26I prepares a further point in the impulsing circuit to the operating magnet 2I2.

The operator now dials the second digit of the called number, in this case the digit 1, to again cause the line relay 290 to deenergize. At back contact 29I, line relay 290 completes a circuit for energizing the operating magnet 2 I2 of the minor switch as follows: from ground by way of back contact 2!, contact 283, back contact 26I, contact 253, and through the winding of operating magnet 2I2 to battery. A branch of this circuit extends through the winding of slow-to-release series relay 2I0 which energizes and at contact 2| I disconnects the switch wipers M3 and 2. In

response to the operation of the operating magnet 2I2 the wipers 2I3 and 2 are stepped one step by means of their ratchet and pawl mechanism in the well known manner into engagement with their first set of bank contacts, and the offnormal springs 2I6 are closed to prepare a point in the circuit for the release magnet 2I5. Line relay 280 remains energized after the impulsing period is terminated so that shortly thereafter the slow-to-release series relay 2I0 restores. At contact 2| I relay 2") completes the circuit for operor ating line relay IIO of the called line in case the called line is not busy. The circuit for energizing line relay IIO may be traced as follows: from ground by way of front contact 215, through the right-hand winding of tick-tone relay 206, contact 2| I, back contact 222, wiper 2I3 in engagement with its first bank contact, conductor I06, back contact I44, through the right-hand winding of line relay H0, conductor I04, contact 28I, and through the winding of relay 200 to battery. Line relay IIO energizes over the above-traced circuit and completes a locking circuit for itself through its right-hand winding from grounded contact H3 by way of conductor I04 and contact 28I through the winding of relay 200 to negative battery. At front contacts III and I I2'line relay IIO connects the subscribers line conductors I82 and I83 to the trunk conductors I02 and I03, while 'at front contact III line relay IIO prepares a point in the circuit for busy relay I08. From the foregoing it will be seen that line relays I I0 and I20 are locked in operated position and connect the two subscribers lines SI I and S I 2 to the upper trunk conductors I02 and I03. 1

In order to complete the connection the remote operator now connects ringing current through the jack J and repeating coils RCI and RC2. to signal both the calling and called subscribers SI2 and SI I. The remote operator may monitor the connection if desired, andgwhen conversation has been completed either the calling or the called subscriber will ring off by operating his hand generator, thereby transmitting ringing generator over the trunk to reoperate the drop 234 at the remote operator's position.

Before describing the release of the connection, it will be assumed that the called subscriber SII was busy in a connection established over the lower trunk line, in which case the line relay I40 will be in operated position. Returning now to the time when the series relay 2I0 deenergizes and the wipers2l3 and 2M have been stepped into engagement with their first set 01' bank contacts, a circuit may now be traced for operating the busy relay I08 since subscriber SII is busy over a connection including the lower trunk line. This circuit may be traced as follows: from ground by way of front contact'215, right-hand winding oftick-tone relay206, contact 2I I, back contact 222, wiper 2I3 in engagement with its first bank contact, conductor I06, front contact I of the operated line relay I40, conductor I08, and through the winding of busy relay I08 and associated resistance to battery. The busy relay I08 energizes over the above-traced circuit,'and at its own contacts short circuits its own winding to cause the busy relay to deenergize, after which it immediately reenergizes over' the previously traced circuit. Busy relay I08 accordingly operates in the manner of a buzzer thereby altering the circuit through the right-hand winding of the tick-tone relay 206 to induce into the lefthand winding of tick-tone relay 206 a tick-tone which is transmitted through the tone condenser TC and over the trunk conductors I02 and I03 to the calling subscriber and the remote operator. This tick-tone informs both the calling subscriber and the remote operator that the called line SI I is busy. In a similar manner the busy relay I08 is operated to transmit the busy signal in case a calling subscriber connected to the lower trunk line attempts a connection to a called subscribers line which is busy in engagement with a connection including the upper trunk line. For example, assuming that the subscriber SI 2 is connected with the lower trunk line I12 and I 13, and desires a connection to subscriber SI I, which is engaged in a connection including the upper trunk conductors I02 and I03. In a manner similar to that described, when the remote operator operates the minor switch associated with the'second trunk line (not shown but indicated in the dotted rectangle in Fig. 1), ground is extended through the action of busy relay I08 induces a tick-tone into the winding of the tick-tone relay'which then transmits the tick-tone to conductors I12 and I 13 to the calling subscriber and to the remote operator.

The. release ,of the established connection is under control of the remote operator. In order to release the established connection the operator removes the plug from the jack J, thereby opening the jack springs 235 to open the circuit to line relay 290 1 which accordingly deenergizes. Line relay 290, upon deenergizing, at front contact 29I opens the circuit of 'slowto-release relay 280, which deenergizes after an interval. At'contacts 28I' relay 280, upon deenergizing, opens the circuit of relay 200 and the lockingcircuits of the line relays H0 and I20 which have been locked to conductor I04 in serieswith relay 200. At contact 282 relay 280 opens the circuit of hold relay 210 and at 283--opens a point in the imof! relay I30 operated, at contact 202 opensa further point in the circuit to the thermo relay 204, and at contact 203 opens a point in the circuit to the tone relay 204. The line relays which were maintained in operated position over their locking windings and conductor I04, now deenergize, and assuming that relays III and I20 are these relays, then the connection from the subscribers lines to the trunk line conductors I02 II2, HI, and I22. At back contacts 2 and I22, line relays H and I20 prepare points in their initial energizing circuits which, however, are still maintained open due to the maintained energization ofcommon cut-off relay I30. From the foregoing it is seen that the line relays H0 and I20 are deenergized in response to the operator removing the plug from the Jack J and that for the time being the subscribers SI2 and SH cannot energize their line relays to initiate a call until such time as the trunk circuit is completely released.

' Shortly after the deenergization of release rea lay 260 hold relay 210 deenergizes and at contact 2" prepares the circuit for relay 200 and the locking circuits of the associated linerelays to enable the subscribers to initiate calls. At contact 212.hold relay 210 disconnects ground from conductor I05 to deenergize the common cut-oil relay I30, at 213 prepares a point in the circuit to the thermo relay 294, and at front contact 214 opens the lockingcircuits of relays.220, 230, 240, and 250, to cause their deenergization if 'and' I03 are interrupted at the front contacts III,

energized, at back contact 214 prepares a point in the circuit to the tone relay 204, at front contact 215 disconnects ground from the minor switch wiper 2I3, and at back contact 215 completes the circuit for energizing the release magnet 2I5 of the minor switch. Release magnet 2I5 ac cordingly operates to cause the wipers of the minor switch to be restored to normal and the off-normal springs 2I6 to be opened. Off-normal springs 2i 6 open the circuit to release magnet 2l5.

Cut-oil relay I30, upon deenergizing, at the back contacts of its armatures, prepares the circuits for enabling the line relays associated with the subscribers lines to be operated in response to further initiation of calls. At back contact I34 the negative pole of the 12-volt battery is con-' nected by way of conductor II", the upper righthand winding of repeating coil RCI, and thence over the trunk conductor 232, through the upper left-hand winding of the repeating coil RC2, to the negative pole of battery at the remote office, thereby constituting a charging circuit for maintaining the rural exchange battery fully charged. It should possibly be mentioned that during the time common cut-off relay I30 is in operated position contact I34 disconnects direct negative battery potential from conductor I 0|, thereby including the balance coil 202 in the trunk to balance both sides of the trunk.

In order to make a reverting call or a call in which one subscriber desires to converse with another subscriber on the same line the calling subscriber initiates the call and signals the operator in the same manner aspreviously described, after which the calling party replaces his receiver and the operator rings back over the trunk line without dialling to signal the desired called subscriber by transmittingthe proper code ring of the called party. The calling and called parties then ring oil to operate the drop, wheresimilar to that described for the upon the operatorremoves the plug and releases the connection as previously described.

The foregoing. has described the circuit operationsv in connection with calls to and from the subscribers in the ten group or the subscriber having a first digit 1. Connections to subscribers in the twenty group or the group in which the first digit is 2 are completed in a similar manner by the remote operator dialling the digit 2 instead of digit 1. The operations are the same as previously described,-bl1t in response to the second impulse of the first digit relay 220 is energized in response thereto since the series relay 260 is maintained energized during the pulsing period. This circuit may be traced as follows: from ground at back contact "I, contact 203, front contact "I, front contact 25I, contact 23I,

and through the winding of relay 220 to battery.

Relay 220. energizes over the above-traced circuit to prepare a circuit for relay 230 at contact 22I, at contact 222 and associated back contact disconnects the wiper 2I3 having access to the lines in the ten group, and at contact 222 and the associated front contact connects up wiper 2 I 4 having access to the lines in the twenty group. When the line relay energizes after the second impulse of the first digit, the short circuit around relay 230 is opened. This short circuit may be traced as follows: ground by way of back contact '29I, contact 283, front contact 26I, front contact 25I, 23I, through the winding of relay 230, contact 22I,'front contact 214 to ground. The reenergization of relay 290 opens this short circuit with the result that relay 230 now energizes in series with relay 220. When the slow-to-release series relay 2I0 deenergizes after completion of the dialling period of the second digit, said relay connects ground by way of armature 215, the right-hand winding of tick-tone relay 206, contact 2, frontcontact 222, wiper 2, and over the individual conductor, not shown, through the line relay in the twenty-line group in a manner ten-line group. and the release to that previously The remainder of the connection of the connection are similar described.

In case the remote operator desires to complete a connection to one of the rural subscribers lines in order to complete a connection between a distant subscriber and a rural subscriber, the operator seizes one of the trunk lines, for instance the upper trunk line, by inserting the plug into'jack J, thereby completing the circuit for line relay 290. Relay 290 causes the operation of the release and hold relays 280 and 210. z

At contact 212 hold relay 210 completes a circuit over conductor I05 for operating the common cut-off relay I30 to prevent any of the rural subscribers from seizing this trunk line. The operator now dials the digits of the called rural line, and assuming that the subscriber SII is the subscriber being called, then the digits 1 and 1 are dialled to cause the wiper M3 to engage conductor I06 in the same manner as previously described. When the slow-to-release series relay 2I0 deenergizes after the impulsing period, the following circuit is completed for energizing the line relay IIO: from ground by way of front contact 215, right-hand winding of tick-tone relay 206, contact 2, back contact 222, wiper 2I3 in engagement with its first bank contact individual to subscriber SI I, conductor I06, back contact I44, through the right-hand winding of line relay 0, conductor I04, contact 28I, and through the winding of relay 200 to battery.

Line relay H and relay 200 energizein series. Relay 200 performs no useful function at this time because it is unnecessary to apply the waiting tone to the line and disconnect it when the operator answers. Line relay H0, upon energizing, at front contact H3 again completes its locking circuit through. its right-hand winding in series with relay 200, and at front contacts Ill and H2 connects subscribers line conductors I82 and I83 to the conductors I02 and I03. The

remote operator now transmits the proper ringing code to signal the desired subscriber, and in response to the called subscriber answering the connection is completed and released as previously described.

In case the remote operator fails to answer "a call within a predetermined time, the thermo relay 294 is operated to cause the release of the locked line relay and the release of the trunk."

When the subscriber Si2 initiates a call line relay I20 and relay 200 energizein series, as previously described. Relay 200 at contact 202 completes a circuit by way of contact 213 for energizing the thermo relay 294. operator answers before a predetermined time, then the hold relay 210 is energized as previouslydescribed to open the circuit to thermo relay 294 to prevent the closure of contact 293. In case, however, the operator fails to answer this call within a predetermined time, then the thermo relay'294 operates and closes its contact 293 thereby completing a circuit for operating the line relay 290 as follows: from ground, through the winding oi line relay 290, contact 293 of the thermo relay to battery. Line relay 290, upon energizing, causes the energization of release and hold relays 280 and 210, as previously described. The latter relay at 213 opens thecircuit of the thermo relay 294, thereby causing the thermo relay to open its contacts 293 and release the line relay 290. Release relay 200 and then later on the hold relay deenergize in the same manner. as previously described. During the interval between the releasing of the release scribers lines, two trunk lines for intercon-- necting said subscribers lines, a pair of line relays individual to each subscribers'line, the first line relay of each pair for directly connecting the corresponding subscribers line to the first of said trunk lines and the second line relay oi each pair for directly connecting'the' corresponding' subscribers line to the second of saidtrunk lines, a first cut-ofi relay individual to said first trunk line and operable when the first trunk line is in use, a second cut-off relay individual to said second trunk line and operable when the second trunk isin use, operating circuits for each of said first line relays associated with the first trunk line normally controlled by said'first cutoff relay, and operating circuits for each of said second line relays associated with the second trunk line jointly controlled by said first and second cut-off relays.

2. In a telephone system, a plurality of sub? In case the scribers lines, two trunk lines for interconnecting said subscribers lines, a pair of line relays individual to each subscribers line, the first line relay of each pair being associated with the first of said trunk lines for directly connecting the corresponding subscribers line to said first trunk line, the second line relay of each pair being associated with thesecond of said trunk lines for directly connecting the corresponding subscribers line to said second trunk line, a first cut-oil relay individual to said first trunk line and operable when said first trunk line is busy, a second cutoff relay individual tosaid second trunk line and operable when said second trunk line is in use, operating circuits for each of said first line relays associated with said first trunk line normally controlled by said first cut-oil relay and the corresponding subscribers second line relay, and operating circuits for each of said second line relays associated with said second trunk line jointly controlled by said first. and second cut-ofl relays and the corresponding subscriber's first line relay.

3. In a telephone system, a plurality of subscribers lines, a plurality of line relays for each subscribers line, said line relays divided into groups each group containing only one line relay for each line, a plurality of cut-off relays common to said lines, one cut-oi! relay for each group of line, relays, an energizing circuit for each line relay in one group including normally closed contacts on the corresponding group cutof! relay and the talking conductors of the corresponding subscribers line; and an energizing circuit for each line relay in another group including normally closed contacts on the corresponding group cut-off relay, normally open contacts on the first mentioned group cut-oi! relay,

and the talking conductors of the corresponding subscribers line.

4. In a telephone system, a plurality of subscribers lines, a plurality of line relays for each subscribers line, said line relays divided into groups each group containing only one line relay foreach line, a plurality of cut-ofl. relays common to saidlines, one cut-ofl relay for each group of line relays; an energizing circuit for each line relay in one group includingthe talking conductors of the corresponding subscribers line, normally closed contacts on the corresponding line relays in each group, and normally closed contacts on the corresponding group cut-oil relay;

and an energizing circuit for each line relay in another group including the talking conductors of the corresponding subscribers line, normally closed contacts on the corresponding line relays in each group, normally open contacts on the first mentioned cut-off relay, and normally closed contacts on the corresponding group cut-off relay.

5. In a telephone system, a plurality of subscribers lines, a plurality of line, relays for each subscribers l ne, a plurality of cut-of! relays common to all saidsubscribers lines, an energizspending subscribers line. Y

6. In a .telephonej'system', a plurality of. subv scribers lines, a plurality'offtrunk lines, an individual subscribers line relay for each trunk line for connecting the subscriberslines to said trunk lines, a cut-ofi relay for each trunk line, each cutoil! relay being common to all said subscribers lines, an automatic switch for each trunk line for selecting called subscribers lines, individual subscriber connections from each switch to said line relays, a first operating circuit for each line relay, including the loop of the corresponding calling subscriber's line and contacts on said common cut-oil? relays, and a second operating circuit for each line relay including said switch and said individual subscriber connections. a

7. In a telephone system, a plurality of subscribers lines, a first and a second line relay for each line, a pair of normally closed contacts on each line relay, a first and a second means for selecting called subscribers lines, individual subscriber connections extending from said first selecting means to one of said contacts on each of said first line relays, individual subscriber connections extending from said second selecting means to one of said contacts on each of said,

second line relays, an operating circuit for each of said first line relays including the corresponding individual connection from said second selecting means and said pair of contacts on the corresponding second line relay, an operating circuit for each of said second line relays including the corresponding individual connection from said first selecting means and said pair of contacts on the corresponding first line relay, and means for operating said selecting means to complete said operating circuits.

8. In a telephone system, a plurality of subscribers lines, a line relay individual to each subscribers line, means for operating the individual line relays in response to corresponding lines initiating calls and being called, a busy relay for generating and transmitting a busy tone to a calling line, normally open contacts on each line relay normally connected to said busy relay, and a circuit including the said normally open con-' tacts on the line relay of the called line for operating said busy relay and completed in case the called line is busy.

9. In a telephone system, a plurality 01' subscribers lines, a line relay individual to each subscribers line, means for operating the individual line relays in response to corresponding lines initiating calls and being called, a busy relay for generating and transmitting a busy tone to a calling line, normally open contacts on each line relay normally connected to said busy relay, a circuit including the said normally open contacts on the line relay of the called line for operating said busy relay and completed in case the called line is busy, and a second circuit inductively coupled to said first circuit for transmitting a busy tone to the calling line.

10. In a telephone system, a plurality of subscribers lines, a first and a second line relay for each line, an armature spring having a front and a back contact'on each line relay, a first and a second means for selecting called subscribers lines, individual subscriber connections extending from said first selecting means to the armature springs on each of said first line relays, individual'subscriber connections extending from said second selecting means to the armature springs on each of said second line -relays, an operating circuit for each of said first line relays including the corresponding individualconnection from said second selecting means and the armature spring and back contact on the corresponding second line relay, an operating circuit 11. In a telephone system, a plurality of subscribers lines, a first and a second line relay for each line, an armature spring having a front and a back contact on each line relay, a first and a second means for selecting called subscribers lines, individual subscriber connections extending from said first selecting means to the armature springs on each of said first line relays, individual subscriber connections extending from said second selecting means to the armature springs on each of said second line relays, an operating circuit for each of said first line relays including the corresponding individual connection from said second selecting means and the armature spring and back contact on the corresponding second line relay, an operating circuit for each of said second line relays including the corresponding individual connection from said first selecting means and the armature spring and back contactv on the corresponding first line-relay, a busy relay common to said lines for generating and transmitting a busy tone to a calling line, and multiple connections connecting each of said front contacts to said busy relay for operating said busy relay in case a busy line is selected by either one of said selecting means.

12. In a telephone system, a plurality of subscribers lines, line relays individual to each line. an armature spring having a front and a back contact on each line relay, means for selecting called subscribers lines, individual subscriber connections extending from said selecting means to said armature springs 01' said line relays, an operating circuit for each line relay including one of said individual subscriber connections and an armature spring and back contact of one of said line relays and completed .in response to said selecting means selecting an idle called line, a busy relay common to said lines for generating and transmitting a busy tone to the calling line, and an operating circuit for said busy relay including one of said individual subscriber connec-' I tions and an armature spring and front contact of one of said line relays and completed in response to said selecting means selecting a busy called line.

a local exchange between local subscribers lines terminating in thelocal exchange, a first and a second trunk line connecting said main and local exchanges, a first line relay individual to a calling local line operated in response to the local line initiating a call for directly connecting said local line to the first trunk line in case the first trunk line is idle, a second line relay individual to said calling local line operated in response to said initiated call for directly connecting said local calling line to said second trunk line in case the first trunk line is busy, and a line relay individual to the called local line operated in response to,

control exercised over said connected trunk lineby the operator for directly connecting the called line to said connected trunk line thereby completing a telephone connection between said local calling and called lines.

14. In a telephone system wherein an operator in a distant main exchange controls the establishment and release of local connections in a local exchange between local subscribers lines terminating in the local exchange, a first and a second trunk line connecting said main and local exchanges, meansindividually associated with a calling local line and. operative in response to the initiation of a call on the associated line for connecting said calling line to said first trunk line in case said first trunk line is idle, means individually associated with said calling line and operative in response to the initiation of the call on the associated line for connecting said calling line to said second trunk line in case the first trunk line is busy, and means individually associated with a called one of said local lines and operative in r$ponse to control exercised by the operator over the one of said trunk lines which is connected to said calling line for connecting the called line to said one trunk line, thereby to complete a telephone connection between said calling and called lines. v

15. In a telephone system, a plurality of subscribers lines, a pair of trunk lines, means associated with each subscribers line and normall responsive to the initiation of a call on the associated line for connecting the associated line to one of said trunk lines, normally inoperative means associated with each subscribers line and adapted to be conditioned to operate in response to the initiation of a call on the associated line to connect the associated line to'the other of said trunk lines, and means responsive to the operation of any one of said first-named means for preventing the other similar first-named means from operating in response to the initiation of calls on their respective associated lines and for conditioning all of the said second-named means for operation. I

16. In a telephone system, a plurality of subscribers lines, a pair of trunk lines, means associated with each subscribers line and normally responsive to the initiation of a call on the associated line for connecting the associated line to one of said trunk lines, normally inoperative means associated with each subscribers line and adapted tobe conditioned to operate in response to the initiation of a call on the associated line operating in response to the initiation of calls on,

their responsive associated lines and for conditioning all of the said second-named means for operation, and operator controlled means for causing any selected one of said first or secondnamed means to operate.

17. In a telephone system, a main exchange, a sub-exchange, a pair ofv trunk lines extendin between said exchanges, an operator's station in said main exchange and associated with said trunk lines, an impulsing deviceat said station, a plurality of subscribers lines extending to said sub-exchange, means associated with each subscribers line and normally responsive to the initiation of a call on the associated line for connecting the associated line to one of said trunk lines, normally inoperative means associated with each subscribers line and adapted to be conditioned to operate in response to the initiation of a call on the associated line to connect the associated line to the other of said trunk lines, means responsive to the operation of any one of said first-named means for preventing the other similar first-named means from operating in response to the initiation of calls on their respective associated lines and for conditioning all of said second-named means for operation, and means responsive to impulses transmitted from said impulsing device over said one trunk line for causing a selected one of said first-named means to operate to connect the associated line to said one trunk line.

18. In a telephone system, a main exchange. a sub-exchange, a pair trunk lines extending between said exchanges, an operator's station in said main exchange and associated with said trunk lines, an impulsing device at said station,

a plurality of subscribers lines extending to said suhexchange, means associated with each subscribers line and normally responsive to the initiation of a call on the associatedline for connecting the associated line to one of said trunk lines, normally inoperative means associated with each subscribers line and adapted to be conditioned to operate in response to the initiation of a call on the associated line to connect the associated line to the other of said trunk lines, means responsive to the operation of any one of said first-named means for preventing the other similar first-named means from operating in response to the initiation of calls on their respective associated lines and for conditioning all of said second-named means for operation, means responsive to impulses transmitted from said impulsing device over said one trunk line for causing a selected one of said first-named means to operate to connect the associated line to said one trunk line, and means responsive to the selection of any one of said means associated with a busy one of said subscribers lines for applying a busy tone current to'said one trunk line and to the calling one of said subscribers lines. 

